Assessment of Digestive and Gastrointestinal Function Part 1'

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Assessment of Digestive andGastrointestinal
FunctionPart 1.

• Second Semester 2ed Years students
• Miss Iman shaweesh
• January 2008

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ANATOMY OF THEGASTROINTESTINAL TRACT

• GI tract is a 23- to 26-foot-long pathway that
  extends from the mouth through the esophagus,
  stomach, and intestines to the anus The esophagus
  is located in the mediastinum in the thoracic
  cavity, anterior to the spine and posterior to
  the trachea and heart. This collapsible tube,
  which is about 25 cm (10 inches) in length,
  becomes distended when food passes through it. It
  passes through the diaphragm at an opening called
  diaphragmatic hiatus.

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• The stomach is situated in the upper portion of
  the abdomen to the left of the midline, just
  under the left diaphragm. It is a distensible
  pouch with a capacity of approximately 1500 mL.
  The inlet to the stomach is called the
  esophagogastric junction it is surrounded by a
  ring of smooth muscle called the lower esophageal
  sphincter (or cardiac sphincter), which, on
  contraction, closes off the stomach from the
  esophagus.

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• The stomach can be divided into four anatomic
  regions
• 1- the cardia (entrance),
• 2- fundus,
• 3- body,
• 4- pylorus (outlet).

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• The small intestine is the longest segment of the
  GI tract,accounting for about two thirds of the
  total length. It folds back and forth on itself,
  providing approximately 7000 cm of surface area
  for secretion and absorption, the process by
  which nutrients enter the bloodstream through the
  intestinal walls. The small intestine is divided
  into three anatomic parts the upper part, called
  the duodenum the middle part, called the
  jejunum and the lower part, called the ileum.
  The common bile duct which allows for the passage
  of both bile and pancreatic secretions empties
  into the duodenum at the ampulla of Vater.

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• The junction between the small and large
  intestine, the cecum, is located in the right
  lower portion of the abdomen. The ileocecal valve
  is located at this junction. It controls the
  passage of intestinal contents into the large
  intestine and prevents reflux of bacteria
• The vermiform appendix is located near this
  junction.

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• The large intestine consists of an ascending
  segment on the right side of the abdomen, a
  transverse segment that extends from
• right to left in the upper abdomen, and a
  descending segment on the left side of the
  abdomen. The terminal portion of the large
  intestine consists of two parts the sigmoid
  colon and the rectum. The rectum is continuous
  with the anus.

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• The GI tract receives blood from arteries that
  originate along the entire length of the thoracic
  and abdominal aorta.
• Of particular importance are the gastric artery
  and the superior and inferior mesenteric
  arteries.
• Oxygen and nutrients are supplied to the stomach
  by the gastric artery and to the intestine by the
  mesenteric arteries

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• Blood is drained from these organs by veins that
  merge with others in the abdomen to form a large
  vessel called the portal vein. Nutrient-rich
  blood is then carried to the liver. The blood
  flow to the GI tract is about 20 of the total
  cardiac output and increases significantly after
  eating.
• Both the sympathetic and parasympathetic
  portions of the autonomic nervous system
  innervate the GI tract. In general, sympathetic
• nerves exert an inhibitory effect on the GI
  tract, decreasing gastric secretion and motility
  and causing the sphincters and blood vessels to
  constrict.

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• Parasympathetic nerve stimulation causes
  peristalsis and increases secretary activities.
  The sphincters relax under the influence of
  parasympathetic stimulation. The only portions of
  the tract that are under voluntary control are
  the upper esophagus and the external anal
  sphincter.

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FUNCTION OF THE DIGESTIVE SYSTEM

• All cells of the body require nutrients. These
  nutrients are derived from the intake of food
  that contains proteins, fats, carbohydrates,
  vitamins and minerals, and cellulose fibers and
  other vegetable matter of no nutritional value.
  The primary digestive functions of the GI tract
  are the following
• To break down food particles into the molecular
  form for digestion

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• To absorb into the bloodstream the small
  molecules produced by digestion
• To eliminate undigested and unabsorbed foods
  tuffs and other waste products from the body
• After food is ingested, it is propelled through
  the GI tract, coming into contact with a wide
  variety of secretions that aid in its digestion,
  absorption, or elimination from the GI tract.

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Chewing and Swallowing

• The process of digestion begins with the act of
  chewing, in which food is broken down into small
  particles that can be swallowed and mixed with
  digestive enzymes. Eatingor even the
  sight,smell, or taste of foodcan cause reflex
  salivation. Saliva is secreted from three pairs
  of glands the parotid, the submaxillary, and the
  sublingual glands. Approximately 1.5 L of saliva
  is secreted daily. Saliva is the first secretion
  that comes in contact with food. Saliva contains
  the enzyme ptyalin, or salivary amylase, which
  begins the digestion of starches

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• Swallowing begins as a voluntary act that is
  regulated by a swallowing center in the medulla
  oblongata of the central nervous system.
• As food is swallowed, the epiglottis moves to
  cover the tracheal opening and prevent aspiration
  of food into the lungs. Swallowing, which propels
  the bolus of food into the upper esophagus, thus
  ends as a reflex action.

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• The smooth muscle in the wall of the esophagus
  contracts in a rhythmic sequence from the upper
  esophagus toward the stomach to propel the bolus
  of food along the tract. During this process of
  esophageal peristalsis, the lower esophageal
  sphincter relaxes and permits the bolus of food
  to enter the stomach.
• Subsequently, the lower esophageal sphincter
  closes tightly to prevent reflux of stomach
  contents into the esophagus.

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Gastric Function

• The stomach stores and mixes the food with
  secretions. It secretes a highly acidic fluid in
  response to the presence or anticipated ingestion
  of food. This fluid, which may have a pH as low
  as 1, derives its acidity from the hydrochloric
  acid (HCl) secreted by the glands of the stomach.

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• The function of this gastric secretion is
• two-fold
• to break down food into more absorbable
  components.
• to aid in the destruction of most ingested
  bacteria.
• The stomach can produce about 2.4 L per day of
  these gastric secretions. Gastric secretions also
  contain the enzyme pepsin, which is important for
  initiating protein digestion.

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• Intrinsic factor is also secreted by the gastric
  mucosa. This compound combines with dietary
  vitamin B12 so that the vitamin can be absorbed
  in the ileum.

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• Peristaltic contractions in the stomach propel
  its contents toward the pylorus. Because large
  food particles cannot pass through the pyloric
  sphincter, they are churned back into the body of
  the stomach. In this way, food in the stomach is
  agitated mechanically and broken down into
  smaller particles.
• Food remains in the stomach for a variable
  length of time, from a half-hour to several
  hours, depending on the size of food particles,
  the composition of the meal, and other factors.

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• This food mixed with gastric secretions is called
  chyme. Hormones, neuroregulators, and local
  regulators found in the gastric secretions
  control the rate of gastric secretions and
  influence gastric motility

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Small Intestine Function

• The digestive process continues in the duodenum.
  Secretions in the duodenum come from the
  accessory digestive organsthe pancreas, liver,
  and gallbladderand the glands in the wall of the
  intestine itself. These secretions contain
  digestive enzymes and bile.

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• Pancreatic secretions have an alkaline pH because
  of high concentrations of bicarbonate. This
  neutralizes the acid entering the duodenum from
  the stomach.
• The pancreas secretes enzymes, including 1-
  trypsin, which aids in digesting protein 2-
  amylase- digesting starch and
• 3- lipase, aids in digesting fats

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• Bile (secreted by the liver and stored in the
  gallbladder) aids in emulsifying ingested fats,
  making them easier to digest and absorb. The
  intestinal glands secrete mucus, hormones,
  electrolytes, and enzymes.
• Intestinal secretions total approximately 1 L/day
  of pancreatic juice, 0.5 L/day of bile, and 3
  L/day of secretions from the glands of the small
  intestine.

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Colonic Function

• Within 4 hours after eating, residual waste
  material passes into the terminal ileum and
  passes slowly into the proximal portion of the
  colon through the ileocecal valve.
• This valve, which is normally closed, helps
  prevent colonic contents from refluxing into the
  small intestine. With each peristaltic wave of
  the small intestine, the valve opens briefly and
  permits some of the contents to pass into the
  colon.
• Bacteria make up a major component of the
  contents of the large intestine. They assist in
  completing the breakdown of waste material,
  especially of undigested or unabsorbed proteins
  and bile salts.

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Waste Products of Digestion

• Feces consist of undigested foodstuffs, inorganic
  materials, water, and bacteria. Fecal matter is
  about 75 fluid and 25 solid material.
• The composition is relatively unaffected by
  alterations in diet, because a large portion of
  the fecal mass is of nondietary origin, derived
  from the secretions of the GI tract. The brown
  color
• of the feces results from the breakdown of
  bile by the intestinal bacteria. Chemicals formed
  by intestinal bacteria (especially indole and
  skatole) are responsible in large part for the
  fecal odor.

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Waste Products of Digestion

• Gases formed contain methane, hydrogen sulfide,
  and ammonia, amongothers. The GI tract normally
  contains approximately 150 mL of
• these gases, which are either absorbed into
  the portal circulation and detoxified by the
  liver or expelled from the rectum as flatus.

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Waste Products of Digestion

• Elimination of stool begins with distention of
  the rectum, which reflexively initiates
  contractions of the rectal musculature and
  relaxes the normally closed internal anal
  sphincter. The internal sphincter is controlled
  by the autonomic nervous system the external
  sphincter is under the conscious control of the
  cerebral cortex. During defecation, the external
  anal sphincter voluntarily relaxes to allow
  colonic contents to be expelled. Normally, the
  external anal sphincter is maintained in a state
  of tonic contraction. Thus, defecation is seen to
  be a spinal reflex (involving the parasympathetic
  nerve fibers) that can be inhibited voluntarily
  by keeping the external anal sphincter closed.

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AssessmentHEALTH HISTORY ANDCLINICAL
MANIFESTATIONS

• Pain
• Pain can be a major symptom of GI disease.
  The character, duration,pattern, frequency,
  location, distribution of referred pain and time
  of the pain vary greatly depending on the
  underlying cause.
• Indigestion Upper abdominal discomfort or
  distress associated with eating (commonly called
  indigestion) is the most common symptom of
  patients with GI dysfunction.

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Indigestion

• result from disturbed nervous system control of
  the stomach or from a disorder in the GI tract or
  elsewhere in the body. Fatty foods tend to cause
  the most discomfort, because they remain in the
  stomach longer than proteins or carbohydrates do.

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Common sites of referred abdominal pain.
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• Intestinal Gas - accumulation of gas in the GI
  tract may result in belching (the expulsion of
  gas from the stomach through the mouth) or
  flatulence (the expulsion of gas from the
  rectum).
• Nausea and Vomitingnausea, which can be triggered
  by odors, activity, or food intake. The emesis,
  or vomitus, may vary in color
• and content. It may contain undigested
  food particles or blood (hematemesis).
• Change in Bowel Habits
• and Stool Characteristics

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Stool is normally light to dark brown.the
ingestion of certain foods and medications, can
change the appearance of stool
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PHYSICAL ASSESSMENT

• includes assessment of the mouth, abdomen,
• and rectum. The mouth, tongue, buccal mucosa,
  teeth, and gums are inspected, and ulcers,
  nodules, swelling, discoloration, and
  inflammation are noted. People with dentures
  should remove them during this part of the
  examination to allow good visualization.
• The patient lies supine with knees flexed
  slightly for inspection, auscultation, palpation,
  and percussion of the abdomen

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Diagnostic Evaluation

• Common blood tests include (CBC),
  carcinoembryonic antigen (CEA),liver function
  tests, serum cholesterol, and triglycerides. Test
  findings may reveal alterations in basal
  metabolic function and mayindicate the severity
  of a disorder.
• The preparation for many of these studies
  (endoscopy or GI laboratory). includes fasting,
  the use of laxatives or enemas, and ingestion or
  injection of a contrast agent or a radiopaque
  dye.

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General nursing interventions for the patient who
is having GI diagnostic assessment include the
following

• Providing general information about a healthy
  diet and the nutritional factors that can cause
  GI disturbances after a diagnosis has been
  confirmed.
• Providing needed information about the test and
  the activities required of the patient.
• Providing instructions about postprocedure care
  and activity restrictions

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• Alleviating anxiety .
• Helping the patient cope with discomfort
• Encouraging family members or others to offer
  emotional.
• support to the patient during the diagnostic
  testing
• Assessing for adequate hydration before, during,
  and immediately after the procedure, and
  providing education about maintenance of
  hydration

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• STOOL TESTS
• BREATH TESTS The hydrogen breath test was
  developed to evaluate carbohydrate
• absorption. It also is used to aid in the
  diagnosis of bacterial overgrowth in the
  intestine and short bowel syndrome. This test
  determines the amount of hydrogen expelled in the
  breath after it has been produced in the colon

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• Urea breath tests detect the presence of
  Helicobacter pylori, the bacteria that can live
  in the mucosal lining of the stomach and cause
  peptic ulcer disease. The patient takes a capsule
  of to 20 minutes later.
• ABDOMINAL ULTRASONOGRAPHY
• Endoscopic ultrasonography (EUS) is a specialized
  enteroscopic procedure that aids in the diagnosis
  of GI disorders by providing direct imaging of a
  target area.

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DNA TESTING

• Researchers have refined methods for genetic risk
  assessment, preclinical diagnosis, and prenatal
  diagnosis to identify persons who
• are at risk for certain GI disorders (eg,
  gastric cancer, lactose deficiency, inflammatory
  bowel disease, colon cancer). In some cases, DNA
  testing allows practitioners to prevent (or
  minimize)

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IMAGING STUDIES

• Imaging studies include x-ray and contrast
  studies, computed tomography (CT) scans, magnetic
  resonance imaging (MRI), and scintigraphy
  (radionuclide imaging).
• Upper Gastrointestinal Tract Study
• Lower Gastrointestinal Tract Study
• Gastrointestinal Motility Studies

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ENDOSCOPIC PROCEDURES

• Fiberscopes are flexible scopes equipped with
  fiberoptic lenses. Fibroscopy of the upper GI
  tract allows direct visualization of the
  esophageal, gastric, and duodenal mucosa through
  a lighted endoscope (gastroscope
• NSG Intervention
• The patient should not eat or drink for 6 to 12
  hours before the examination

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NSG Intervention

• Patient preparation includes helping the patient
  spray or gargle with a local anesthetic, and
  administering midazolam (Versed) intravenously
  just before the scope is introduced.
• Midazolam is a sedative that provides moderate
  sedation and relieves anxiety during the
  procedure
• The nurse positions the patient on the left side
  to facilitate saliva drainage and to provide easy
  access for the endoscope.

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• After the procedure, the nurse instructs the
  patient not to eat or drink until the gag reflex
• returns (in 1 to 2 hours), to prevent
  aspiration of food or fluids into the lungs. The
  nurse places the patient in the Simms position
  until he or she is awake and then places the
  patient in the
• semi-Fowlers position until ready for
  discharge.

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ENDOSCOPIC PROCEDURES

• Anoscopy, Proctoscopy, and Sigmoidoscopy
• The lower portion of the colon also can be viewed
  directly to evaluate rectal bleeding, acute or
  chronic diarrhea, or change in bowel patterns and
  to observe for ulceration, fissures, abscesses,
  tumors, polyps, or other pathologic processes.
  Rigid or flexible fiberoptic scopes can be used.
  The anoscope is a rigid scope that is used to
  examine the anus and lower rectum. Proctoscopes
  and sigmoidoscopes are rigid scopes that are used
  to inspect the rectum
• and the sigmoid colon.
• )

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